Building the Training Blueprint
Building the Blueprint
Using physiological testing to map an athlete's strengths, weaknesses, and the four levels of their energetic "house."
In the previous post, we explored how physiological testing helps set individualized training zones. But testing reveals far more than zone boundaries. It gives us a comprehensive map of what's happening inside the athlete, and a blueprint for where to direct the training next.
By analyzing changes in heart rate, lactate, and fat oxidation across the intensity spectrum, we can gain insights into the cardiovascular and muscular systems: where the heart reaches maximum stroke volume, how fiber types shift with intensity, and what the glycogen "cost" of different zones looks like. This leads us to the next question: now that we can measure these things, what do we want to see?
Four Levels of Energy Production
Different sports and events require different levels of energy production, but all require sufficient "room to grow." I find it useful to think of the athlete's energetic profile as a house with four levels, each built on top of the one below.
Anaerobic Power (the Roof) is the maximal ability of all fibers to produce force. It represents the ultimate ceiling. Aerobic Power/VO2max (the Attic) is the maximal ability to produce power aerobically. Threshold (the Main Floor) is the maximal semi-sustainable power without increasing acidosis. And Fat Burning (the Foundation) is the maximal sustainable power without glycogen depletion.
Every higher level depends on the one below it. You can't have a high VO2max without sufficient muscle mass. You can't have a strong threshold without adequate VO2max. And the whole structure rests on metabolic health. Let's look at each level in detail.
Anaerobic Strength and Power
It starts with a simple truth: muscle moves stuff. The amount of muscle required depends on the task. Once the "clay" (muscle mass) is there, it can be molded in different ways: trained to operate slowly and steadily (aerobically), or quickly and forcefully (glycolytically). But the molding process starts with sufficient clay.
There's a strong relationship between muscle mass and VO2max. Even the most aerobically fit athletes struggle to surpass an oxygen uptake of about 200 ml/min per kilogram of appendicular mass. This sets a hard requirement. A world-class heavyweight rower needing 7 liters/min of VO2max requires at least 35 kg of appendicular muscle. This is why elite rowing programs include extensive weightlifting to build the raw material that will later be developed aerobically.
"The legs feed the wolf."
– Herb Brooks, in the movie Miracle
In order for the "wolf" (the heart) to grow, the oxygen demand from the muscles must grow first. When we see athletes unable to push much beyond the anaerobic threshold in a step test, or who achieve significantly higher heart rates on the treadmill than on the bike, it generally indicates a peripheral muscle mass limitation.
Testing anaerobic power: the VLaMax test
A 15-second all-out effort with lactate samples before and after. The difference in lactate divided by the effective anaerobic duration (test time minus ~4 seconds for the alactic component) gives a number usually between 0.3 and 1.5 mmol/L/s. For example: starting lactate of 1.0, ending lactate of 10.0, over 15 seconds yields (10-1)/(15-4) = 0.8 mmol/L/s.
Elite endurance athletes move in the opposite direction over time, developing "lactate-gobbling" slow-twitch fibers that progressively reduce maximal lactate production. Typical VLaMax values for elite Ironman athletes are around 0.3 mmol/L/s. That said, this is a specialized adaptation the athlete should be in no hurry to reach. For developing athletes, keeping the fast-twitch fibers "alive" is important.
Aerobic Power (VO2max)
Muscle alone is not enough. It must be aerobically conditioned: sufficiently rich in mitochondria and capillaries to process the pyruvate being generated and keep the metabolism aerobic. VO2max is the product of two factors (the Fick equation): cardiac output (how much oxygen the heart can deliver) and the a-VO2 difference (how much of that oxygen the muscles can extract).
For whole-body, large-muscle-mass exercise, the ratio of central to peripheral contribution is roughly 2:1. The vast majority of the difference in VO2max between well-trained endurance athletes and untrained individuals comes from the cardiac side, specifically, from an increase in maximal stroke volume.
Reading the heart rate curve over time
Since the oxygen cost of a given power output remains relatively constant, fewer heartbeats at the same power generally indicates a larger stroke volume. Tracking the heart rate curve from test to test over months and years provides useful indirect information about cardiac development.
A 10 bpm reduction at 350 watts translates, through the Fick equation, to roughly a 6% increase in functional heart size. Typical stroke volume ranges from ~100ml in untrained individuals to 180ml with extensive training, and beyond 200ml in larger, very well-trained athletes.
Threshold: Aerobic Glycolytic Capacity
The lactate curve reveals fiber recruitment patterns in real time. Below the aerobic threshold, recruitment is almost exclusively slow-twitch, and lactate is low and stable. As intensity exceeds what slow-twitch fibers can handle alone, fast oxidative glycolytic (FOG) fibers are recruited, producing a gentle rise in lactate. At the anaerobic threshold, fast glycolytic fibers join in, and the curve steepens sharply.
For developing athletes, I recommend working toward a "balanced" curve: aerobic threshold at approximately 60% of VO2max power and anaerobic threshold at approximately 85%. This provides well-developed slow-twitch fibers while still maintaining room to grow. In the early season, the focus for most athletes means a lot of aerobic work, aligning nicely with the goal of growing cardiac volume.
Fiber type and the shape of the curve
There is enormous natural, genetic variation in fiber type distribution. Simoneau and Bouchard found that slow-twitch content ranges from 15% to 85% in the population, with about 45% of the variation attributable to genetics. This profoundly shapes the lactate curve.
Tour de France GC Contender
A recent yellow jersey contender showed a maximal power of 473W (estimated VO2max of ~89 ml/kg/min). His aerobic threshold occurred at 353W (75% of max) and his anaerobic threshold at 413W (87% of max), both considerably higher than the balanced athlete norms of 60% and 85%. His maximal lactate of only 5.5 mmol/L confirms a strongly slow-twitch phenotype, similar to elite Ironman triathletes. Based on his curve, he is physiologically well-suited for stage racing: exactly what his palmares reflect.
The intelligent athlete works with their natural fiber distribution and selects events that match it. Research by Baguet (2011) showed fiber type differences ranging from 73-78% slow-twitch in Ironman athletes down to 33-45% in 400m runners. Genetics plays a major role, and advances in genomics (particularly the ACTN-3 polymorphism) are making it increasingly possible to identify an athlete's predisposition early.
Metabolic Health and Fat Oxidation
A house is only as strong as its foundation. Metabolic health and fat oxidation capacity underpin everything else. Energy availability plays a crucial role in improvement: an athlete can only work as hard as their body allows them to recover from. Good metabolic fitness preserves glycogen stores for recovery and high-intensity training, and for events lasting longer than 90 minutes, glycogen depletion becomes a primary performance limiter.
When evaluating metabolic health, two qualities matter most: high levels of fat oxidation at rest and low intensities (to conserve glycogen), and broad fat oxidation at race-specific intensities (for events over 90 minutes).
The mean maximal fat oxidation at AeT is approximately 4 kcal/min. At VT1, it drops to about 3 kcal/min. Rates above 8 kcal/min are very rare (~5% of the sample). Roughly 20% of all athletes tested fall at or below 2 kcal/min, which represents metabolically unhealthy territory.
Research by Inigo San Millan compared fat oxidation in professional cyclists (averaging 6.3 kcal/min at 250W), moderately active healthy individuals (3.6 kcal/min at 140W), and individuals with metabolic syndrome (1.8 kcal/min at 110W). The gap is enormous, and roughly 20% of all athletes in my own lab fall into the metabolically unhealthy range.
Building the Complete Athlete Profile
With results from the full battery of tests, we can assemble a comprehensive profile of the athlete's strengths and weaknesses across all four levels. For a young-training-age athlete just getting back into shape, it might show adequate strength and anaerobic power but significant deficits in aerobic base measures like AeT, AnT, and fat oxidation. This immediately tells us where to direct the training.
For athletes early in development, the focus should be on achieving balanced fitness across all areas: building well-rounded athletes before specializing. For more experienced athletes competing in specific events, the training can be targeted at specific benchmarks. Think of it as having the blueprint for building a sturdy house. With the blueprint in hand, we can identify which walls need reinforcing and make the necessary changes.
In the next post, we'll examine how body type and composition influence sport and event selection, and then we'll get into the specifics of designing an individualized training plan that addresses each athlete's unique profile.